size of array

[freelancelote]

Hi,

is it possible to find out the size of an array created on the free store?

thanks

[Narue]

Not without resorting to non-portable solutions. Just do what everyone else does and don't lose the size that was passed to the allocation function.

[freelancelote]

Thanks Narue,
any chance to know why that is?

Also, the function I have to do takes an array as a parameter and needs to know the size of the array and then loop through all members of it. Have you got a suggestion on how to do it?

[Salem]

Pass the size as a parameter. void foo ( char *buff, size_t size ); kinda thing.

[Narue]

>any chance to know why that is?
No, no chance at all.

[freelancelote]

Salem,
I don't know the size and it's exactly what I'm trying to find out (I'm trying to build a function that takes an array as a parameter, finds out the size of the array and loops through all members of it)

[Narue]

>I don't know the size
Change your code so that you do. Put simply, if you don't know the size of an array parameter in a function you wrote, you've written bad code.

[Salem]

Unless it's an array of chars, which if you regard it as a string, is conventionally marked at the end with a \0, then you're stuck.

Given void foo ( char *p ); Then

char a[10];
char *p = malloc( 20 );
foo( a );
foo( p );

As far as foo() is concerned, there's nothing standard to tell what kind of memory it is, or how big that memory is.

Further, this is also valid foo ( &p[5] ); which would almost certainly break any non-standard API which only worked on the result of malloc calls.

[dmanw100]

You can loop through a string and find the '/0' though, correct?

[Nick Evan]

You can loop through a string and find the '/0' though, correct?

Almost. You can loop through a c-style-string (an array of char) and find the '\0' (backslash) to find it's length. But you could also use strlen() which is a function specially made for this :)

[freelancelote]

Hi,
thanks for the answers,